Bleaching of Substrates

ABSTRACT

The present invention concerns the treatment of substrates with a preformed transition metal catalyst in an aqueous solution. The transitional metal catalyst is a dinuclear Mn transitional metal catalyst and its ligand has the following formula (I): 
     
       
         
         
             
             
         
       
     
     and p is 3.

FIELD OF INVENTION

The present invention relates to the catalytic oxidation and/orbleaching of substrates.

BACKGROUND OF INVENTION

U.S. Pat. Nos. 5,516,738 and 5,329,024 disclose the use of a manganesetransition metal catalyst of 1,4,7-Trimethyl-1,4,7-triazacyclononane(Me₃-TACN) for epoxidizing olefins; the transition metal catalyst has asa non-coordinating counter ion ClO₄ ⁻. U.S. Pat. No. 5,329,024 alsodiscloses the use of the free Me₃-TACN ligand together with manganesechloride in epoxidizing olefins.

WO 2002/088063, to Lonza A G, discloses a process for the production ofketones using PF₆ ⁻ salts of manganese Me₃-TACN.

WO 2005/033070, to BASF, discloses the addition of an aqueous solutionof Mn(II)acetate to an aqueous solution of Me₃-TACN followed by additionof a organic substrate followed by addition of hydrogen peroxide.

WO2006/125517 discloses the use of manganese complexes with1,4,7-Trimethyl-1,4,7-triazacyclononane (Me₃-TACN) and1,2-bis-(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)-ethane (Me₄-DTNE) ashighly-water soluble salts in bleaching.

WO08086937 and EP1934396B both disclose oxidative/bleaching processeswith manganese complexes with 1,4,7-Trimethyl-1,4,7-triazacyclononane(Me₃-TACN) and 1,2-bis-(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)-ethane(Me₄-DTNE) salts.

R. Hage et al. in Nature, 369, 637 (1994) teaches the optimal use ofmanganese complexes containing Me₃-TACN to be at around pH 10.0-10.5 andfor the manganese complex containing Me₄-DTNE to be at around pH 11.0

SUMMARY OF INVENTION

The present method provides a method of bleaching of cellulosicsubstrates, of treatment of effluent waste streams, removal of starchesand polyphenolic substrates from hard surfaces, modification of starch,oxidations of alkenes into epoxides and/or diols and/or dicarboxylicacids, alcohol into aldehyde and/or carboxylic acids, alkanes intoalcohols and ketones.

We have found that by using a preformed manganese transition metalcatalyst at a high pH permits effective bleaching such that levels ofthe preformed manganese transition metal catalyst may be kept at aminimum.

In one aspect the present invention provides a method of treating asubstrate comprising the following step: contacting the substrate withan aqueous medium, having at least 1% of water and from 1 to 1500 mM ofhydrogen peroxide, to form an oxidative medium, the aqueous mediumcomprising a transition metal catalyst, wherein the transition metalcatalyst is preformed and a dinuclear Mn(II)Mn(II), Mn(II)Mn(III),Mn(III)Mn(III), Mn(III)Mn(IV) or Mn(IV)Mn(IV) transition metal catalyst,the ligand of the transition metal catalyst of formula (I):

p is 3;

R is independently selected from: hydrogen; C1-C6-alkyl, C2OH; C1COOH;and, pyridin-2-ylmethyl and one of R is linked to the N of another Qfrom another ring via an ethylene bridge;

R1, R2, R3, and R4 are independently selected from: H; C1-C4-alkyl; and,C1-C4-alkylhydroxy, wherein the oxidative medium has a pH in the range11 to 13 and the concentration of the transition metal catalyst is inthe range from 0.0001 to 1.5 microM.

The transition metal catalyst may be a single transition metal catalystor a mixture of the transition metal catalysts as defined above.

DETAILED DESCRIPTION OF THE INVENTION Transition Metal Catalyst

The manganese transition metal catalyst used may be non-deliquescent byusing counter ions such as PF₆ ⁻ or ClO₄ ⁻, it is preferred forindustrial substrates that the transition metal complex is watersoluble. It is preferred that the preformed transition metal is in theform of a salt such that it has a water solubility of at least 50 g/l at20° C. Preferred salts are those of chloride, acetate, sulphate, andnitrate. These salts are described in WO 2006/125517.

It will be understood from the foregoing description that begins offormula (I) may alternatively be represented by the following structure:

wherein R, R1, R2, R3, and R4 are as herein defined.

Preferably R is independently selected from: hydrogen, CH3, C2H5,CH2CH2OH and CH2COOH.

More preferably R, R1, R2, R3, and R4 are independently selected from: Hand Me.

Most preferably, the catalyst is derived from the ligand1,2,-bis-(4,7,-dimethyl-1,4,7,-triazacyclonon-1-yl)-ethane (Me-4-DTNE).

The preformed transition metal catalyst salt is preferably a dinuclearMn(III) or Mn(IV) complex with at least one O²⁻ bridge. For example, thepreformed transition metal catalyst salt may be a salt of the metalcomplex [Mn^(III)Mn^(IV)(μ-O)₂ (μ-CH₃COO) (Me₄-DTNE)]²⁺.

Preferably, the pH of the oxidative medium is from pH 11.2 to 12.8, morepreferably from pH 11.5 and 12.5.

Preferably, the concentration of the transition metal catalyst is from0.0005 to 1 microM, more preferably from 0.001 to 0.7 microM.

Substrates

Cellulosic substrates are found widely in domestic laundry, industrialand institutional laundry, wood-pulp, cotton processing industries andthe like. Although target cleaning can be different, it is the objectivein all cases to bleach these substrate, i.e., either removing undesiredstains or solids (laundry applications), or bleaching polyphenolicsubstrates that are present in the natural cotton materials (raw cottonand wood pulp).

For laundry (both domestic as well as institutional & industrialcleaning), bleaching agents are used for cleaning and hygiene purposes.Especially hydrogen peroxide and peracids are being employed widely. Ashighlighted above, hydrogen peroxide can be activated by catalysts toallow cleaning at lower bleaching temperatures.

The term “crockery” encompasses plates, dishes and other eating (e.g.,cutlery) and serving tableware, usually made of some ceramic material;crocks, earthenware vessels, especially domestic utensils.

Synthetic Applications

Although not limited, examples include alkene oxidations into epoxide,cis-diol, trans-diol (formed from the epoxide upon alkaline hydrolysis),and via C—C cleavage into the carboxylic acid. Examples (but not limitedto these examples) of alkenes to give epoxide include cycloocteneconversions, styrene, 1-octene, dimethylmaleate. It should be notedthat, as persons skilled in the art will appreciate, that these epoxidesmay be hydrolysed into trans-diol groups.

In this regard, alkenes, aldehydes, and alkanes are preferred substratesand it is preferred that when these substrates are oxidised they arepresent (including isomers and enantiomers) at least 90% purity; thislevel of purity does not include the oxidative medium.

This invention is supported by the following non-limiting examples.

EXPERIMENTAL

[Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ was obtained as disclosed elsewhere(K.-O. Olivier et al., J. Am. Chem. Soc., 120, 13104-13120 (1998)).

Experiment 1 Bleaching of Pulp with Very Low Levels of Catalyst([Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂) Softwood Pulp

Softwood pulp with a starting ISO-brightness of 84.3 was treated asfollows: 1 g of oven-dry pulp was added to a series of mini-bottlescontaining various levels of catalyst, 4 kg/t H₂O₂ (equals to 5.9 mMH₂O₂), and 0.5 kg/t DTPMP (Diethylenetriaminepenta(methylene-phosphonicacid)—(ex Solutia; trade name Dequest 2066; purity is 32%). ThepH-values were adjusted to desired level @pH 11.5 (measured at 20° C.).

Note 1: This softwood pulp has been delignified in a O₂-delignificationstep, and partly further bleached by a ClO₂ step, a Ep(H₂O₂) and a ClO₂step.

Note 2: In practice, pulp was used that contained 30% dry matter and 70%water (30% dry content). Therefore 3.33 g of ‘wet’ pulp was used foreach experiment.

Note 3: All experiments were carried out at 5% consistency.

The mini-bottles are put in a pre-heated water bath (70° C.) for 1 hourand are shaken throughout the bleaching process. Subsequently the pulpmixture is filtrated through a Buchner funnel, washed with copiousamounts of demineralised water and dried overnight at ambientconditions. The optical properties of the pulp heaps were then measuredusing a Minolta spectrophotometer CM-3700d, using L, a, b values whichare converted to whiteness values through the following formula:

100−√{square root over ((100−L)² +a ² +b ²)}

The ISO-Brightness values are calculated through the following formula:

ISO-Brightness=(1.98*whiteness)−100.3

The results of the experiment are given in Table 1.

TABLE 1 ISO-Brightness results of bleaching softwood pulp using variouslevels of [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ at pH 11.5 at 70° C. for 60minutes. The error of the experiments is around 0.4 ISO Brightnessvalues. [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ Brightness (micromolar) (ISO %)0 (blank) 86.4 0.06 87.2 0.12 87.3 0.3 87.9

Eucalyptus Hardwood Pulp

The same set of experiments were conducted using eucalyptus hardwoodpulp (starting brightness of 72.0% ISO). In the solutions various levelsof catalyst were added and 3 kg/t H₂O₂ (equals to 4.4 mM H₂O₂). ThepH-values were adjusted to desired level @pH 11.6 (measured at 20° C.).

Note 1: This eucalyptus pulp has been delignified in aO₂-delignification step, and partly further treated by an acidic washand a ClO₂ step.

Note 2: In practice, pulp was used that contained 31.4% dry matter and68.6% water (31.4% dry content). Therefore 3.18 g of ‘wet’ pulp was usedfor each experiment.

Note 3: All experiments were carried out at 5% consistency.

The results of the experiment are given in Table 2.

TABLE 2 ISO-Brightness results of bleaching eucalyptus hardwood D1 usingvarious levels of [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ at pH 11.6 at 85° C.for 90 minutes. [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ Brightness (micromolar)(ISO %) 0 (blank) 81.5 (0.11) 0.16 83.0 (0.12) 0.4 83.3 (0.04)

An additional set of experiments was carried out using another batch ofeucalyptus hardwood pulp (starting brightness of 71.5% ISO), that hasbeen treated before with hot ClO₂. This set of bleaching experiments wasalso carried out at 5% consistency, but now using 5 kg/t H₂O₂. Theresults of these bleaching experiments are given in Table 3.

TABLE 3 ISO-Brightness results of bleaching eucalyptus hardwood D1 usingvarious levels of [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ at pH 12.0, 12.5, and13.0 at 80° C. for 90 minutes. [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂Brightness (% ISO) pH 12.0; 0 μM 80.7 (0.4)—4 pH 12.0; 0.0005 μM 81.3(0.1)—4 pH 12.0; 0.05 μM 82.2 (0.3)—4 pH 12.5; 0 μM 80.7 (0.6)—4 pH12.5; 0.008 μM 82.3 (0.0)—4 pH 12.5; 0.08 μM 83.4 (0.1)—2 pH 13.0; 0 μM80.3 (0.2)—4 pH 13.0; 0.025 μM 82.5 (0.5)—2 pH 13.0; 0.082 μM 83.0(0.4)—2

Experiments are done in fourfold or two-fold (values given afterstandard deviations).

The results gathered in Table 1 and 2 show that the addition of[Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ at very low levels leads to an increasein Brightness of the pulp samples as compared to the references. Evenlevels as low as 0.06 microM gives a significant bleach effect underthese conditions.

Moreover, the results gathered in Table 3 show that the addition of[Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ at levels as low as 0.0005 microM give asignificant bleach effect under these conditions. Further, these datashow that at pH 11.6, 12.0, pH 12.5, and pH 13.0, a significant benefitof the catalyst can be obtained.

Experiment 2

Raw cotton with a Berger Whiteness value of 7.5+/−1.0 was treated asfollows: 2 grams of the cotton was immersed into mini-bottles containinga 20 ml solution (cloth/liquor ratio of 1/10) containing various levelsof [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂, 35 mM to 120 mM H₂O₂ (equals to 3 to10 ml/l 35% w/w H₂O₂), pH-value adjusted to desired level, 1 g/lSandoclean PCJ (ex Clariant). Different levels of Dequest 2066 wereused: 0.9 g/l Dequest 2066, ex Solutia (purity of 32%) was used(=DTPMP—Diethylenetriaminepenta(methylene-phosphonic acid) for the datagiven in table 4. For the experiments shown in table 5, 0.3 g/l Dequest2066 solution was used.

The mini-bottles were put in a pre-heated water bath (77° C.) for 30 to35 minutes (the temperature of the bleaching solutions in the bottles isthen 75° C.). Subsequently the cotton swatches were rinsed twice with 1litre of hot demineralised water (95° C.), then with 1 litre of 40° C.demineralised water containing 1 ml/l acetic acid and then washed withcopious amounts of demineralised water and dried overnight under ambientconditions. The optical properties of the cloths were then measuredusing a Minolta spectrophotometer CM-3700d, using X, Y, Z values whichare converted to Berger Whiteness values.

The values of the whiteness are expressed in Berger units. The formulaof Berger whiteness is given below:

W _(berger) =Y+a·Z−b·X, where a=3.448 and b=3.904.

The values X, Y, Z are the coordinates of the achromatic point. Theresults of the experiments are given in Table 4.

TABLE 4 Berger Whiteness results of bleaching raw cotton using variouslevels of [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ at various pH's at 75° C. for30 to 35 minutes. Reaction [Mn₂O₂(CH₃COO)(Me₄- Peroxide timeDTNE)](PF₆)₂ Whiteness (mmolar) (minutes) pH (micromolar) (Berger) 75 3011.0 0 (blank) 54.7 ± 1.2 75 30 11.0 0.1 57.5 ± 0.8 75 30 11.0 0.25 59.4± 0.6 75 30 11.0 0.5 59.2 ± 0.7 75 30 11.0 1 61.5 ± 0.1 75 30 11.0 1.561.2 ± 0.5 75 30 12.0 0 (blank) 60.6 ± 0.8 75 30 12.0 0.1 63.5 ± 0.6 7530 12.0 0.25 65.6 ± 0.7 75 30 12.0 0.5 66.8 ± 0.6 75 30 12.0 1 68.6 ±0.6 75 30 12.0 1.5 69.7 ± 0.6 120 35 12.0 0 (blank) 68.1 ± 1.0 120 3512.0 0.1 70.3 ± 0.7 120 35 12.0 0.25 71.8 ± 0.4 120 35 12.0 0.5 73.3 ±0.2 120 35 12.0 1 74.0 ± 0.8 120 35 12.0 1.5 74.5 ± 0.6 35 35 12.0 0(blank) 52.5 ± 0.7 35 35 12.0 0.1 55.8 ± 0.5 35 35 12.0 0.25 56.8 ± 0.735 35 12.0 0.5 58.6 ± 0.7 35 35 12.0 1.0 60.3 ± 0.4 35 35 12.0 1.5 61.1± 0.6 58 35 12.0 0 (blank) 59.3 ± 1.1 58 35 12.0 0.1 62.9 ± 0.9 58 3512.0 0.25 64.1 ± 0.3 58 35 12.0 0.5 64.7 ± 0.7 58 35 12.0 1 66.9 ± 0.558 35 12.0 1.5 67.8 ± 0.9

The results gathered in Table 4 show that under the range of pH andlevels of peroxide tested the addition of[Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ always leads to an increase in thewhiteness of the swatches versus the blank (without catalyst), even withvery low levels (an increase by 2-3 Berger is obtained by addition ofonly 0.1 micromol/L of the catalyst).

TABLE 5 Berger Whiteness results of bleaching raw cotton using variouslevels of [Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ at various pH's at 75° C. for30 minutes. Reaction time [Mn₂O₂(CH₃COO)(Me₄- Whiteness H₂O₂ (mM)(minutes) pH DTNE)](PF6)₂ (μM) (Berger) 75 30 12.5 0 (blank) 61.6 ± 0.475 30 12.5 0.05 63.4 ± 0.9 75 30 12.5 0.1 65.1 ± 0.5 75 30 12.5 0.5 68.2± 0.4 75 30 12.5 1 69.8 ± 0.7 75 30 12.5 2 71.3 ± 0.6 75 30 13.0 0(blank) 61.4 ± 0.6 75 30 13.0 0.05 63.2 ± 0.7 75 30 13.0 0.1 65.8 ± 0.575 30 13.0 0.5 68.3 ± 0.4 75 30 13.0 1 70.2 ± 0.3

Taken together, the results gathered in Tables 4 and 5 show that, underthe range of pH and levels of peroxide tested, the addition of[Mn₂O₂(CH₃COO)(Me₄-DTNE)](PF₆)₂ always leads to an increase in thewhiteness of the swatches versus the blank (without catalyst), even atpH 12.5 and 13.0. Even with very low levels of catalyst (0.05 μM) anincrease by 2-3 Berger is obtained.

Overall, the data support the claim on the range of pHs to be applied(11.0-13.0), ranging from low end (data on pH 11—table 4; pH 11.6—table1 and 2, pH 12.0/pH 12.5/pH 13.0—tables 2, 3, 4, 5) and on the range ofcatalyst that can give significant benefits (from 0.0005 μM—table 3,till 1.5 μM—tables 4 and 5).

1. A method of treating a substrate comprising the following step: contacting the substrate with an aqueous medium comprising at least 1% of water, from 1 to 1500 mM of hydrogen peroxide, and a preformed transition metal catalyst to form an oxidative medium; wherein the transition metal catalyst is a dinuclear Mn(II)Mn(II), Mn(II)Mn(III), Mn(III)Mn(III), Mn(III)Mn(IV) or Mn(IV)Mn(IV) transition metal catalyst having a ligand of formula (I):

p is 3; R is independently selected from the group consisting of: hydrogen, C₁-C₆-alkyl, CH₂CH₂OH, CH₂COOH, and pyridin-2-ylmethyl; and one of R is linked to the N of another Q from another ring via an ethylene bridge; R₁, R₂, R₃, and R₄ are independently selected from the group consisting of: H, C₁-C₄-alkyl, and C₁-C₄-alkylhydroxy; and wherein the oxidative medium has a pH in the range 11 to 13 and the concentration of the transition metal catalyst is in the range from 0.0001 to 1.5 microM.
 2. The method according to claim 1, wherein R is independently selected from: hydrogen, CH₃, C₂H₅, CH₂CH₂OH and CH₂COOH.
 3. The method according to claim 1, wherein R, R₁, R₂, R₃, and R₄ are independently selected from: H and Me.
 4. The method according to claim 1, wherein the catalyst is derived from 1,2,-bis-(4,7,-dimethyl-1,4,7,-triazacyclonon-1-yl)-ethane (Me-4-DTNE).
 5. The method of treating a substrate according to claim 1, wherein the pH of the oxidative medium is from pH 11.2 to 12.8.
 6. The method of treating a substrate according to claim 5, wherein the pH of the oxidative medium is from pH 11.5 and 12.5.
 7. The method of treating a substrate according to claim 1, wherein the concentration of the transition metal catalyst is from 0.0005 to 1 microM.
 8. The method of treating a substrate according to claim 7, wherein the concentration of the transition metal catalyst is from 0.001 to 0.7 microM.
 9. The method according to claim 1, wherein the preformed transition metal catalyst salt is a dinuclear Mn(III) or Mn(IV) complex with at least one O²⁻ bridge.
 10. The method according to claim 1, wherein the preformed transition metal catalyst salt is a salt of the metal complex [Mn^(III)Mn^(IV)(μ-O)₂(μ-CH₃COO)(Me₄-DTNE)]²⁺.
 11. The method according to claim 1, wherein the substrate is selected from the group consisting of: cellulosic substrate, crockery.
 12. The method according to claim 11, wherein the substrate is a cellulosic substrate or crockery.
 13. The method according to claim 1, wherein the treating of the substrate occurs in a mechanical dishwasher.
 14. The method according to claim 4, wherein the pH of the oxidative medium is from pH 11.2 to 12.8.
 15. The method of treating a substrate according to claim 4, wherein the concentration of the transition metal catalyst is from 0.0005 to 1 microM.
 16. The method according to claim 4, wherein the preformed transition metal catalyst salt is a dinuclear Mn(III) or Mn(IV) complex with at least one O²⁻ bridge.
 17. The method according to claim 4, wherein the substrate is selected from the group consisting of: cellulosic substrate, crockery. 